> That is precisely the point. Death is an integral part of what life is. Yet> I never her the proponents of "life-in-a-test-tube" talk about it. Death is> the cessation of life. You see, such deep issues are always circular.>

Which is exactly why biologists do not discuss it. Biology is the science of
life; hence biologists cannot study it when it no longer exists. Nor can
they study something that cannot be measured or experimented with. Death is
part of life only in that death is what you have when life stops. As such,
no one can say what it is, only what it is not. Like any science, biology
can only study what is; it cannot study what is not. Death is not a physical
concept like life; it is metaphysical, and science cannot study metaphysical
concepts.

Besides, as you admit your argument is circular. You are saying that to
prove protocells are alive we have to show that they can die, but before we
can do that we must prove that they are alive in the first place. In other
words, since death is the cessation of life, to use death to prove the
existence of life we have to know that life exists and thus can cease.
That's why it is better to define life by what it does, not by what you have
when it stops doing what it does. Which is exactly what Fox accomplished.
As such, knowing that his protocells are alive, we can now also say that they
can die.